Machine tool control



M 'rch'27, 1945. c. JOHNSON v 2,372,427 MACHINETOOL coumou I Filed S pt. 25, 1941 7 Sheets-Sheet 1 FIGQ , v Snventor CLARENCE JOHNSON March 27, 1945. CLJOHNSON 2,372,427

MACHINE TOOL CONTROL Filed Sept, 23, 1941 7 Sheets-Sheet 2 3nventor CLARENCE JOHNSON Max:527, 1945, c. JOHNSON MACHINE TOOL CONTROL Filed Sept. 25, 1941 7 Sheets-Shed 4 v I Q CLARENCE JOHNSON March 27, 1945. QIJQHNSQN 2,372,427

MACHINE TOOL CONTROL Filed Sept. 25, 1941 7 Sheets-Sheet 5 I Zhwetitor ENCE JOHNSON Fm. 6 M/MM March 27, 1945. c. JOHNSON MACHINE TOOL CONTROL 7 Sheets-Sheet 6 Filed Sept. 23, 1941 ZSnventor CLARENOCE Marchl27, 1 945. c. JOHNSON MACHINE TOOL CONTROL *Filed Sept. 25, 1941 '7 Sheeis -Sheet 7 FIG.

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CLARENCE JOHNSON C(ttorneg Patented Mar. 27, 1945 MACHINE TOOL CONTROL Clarence Johnson, South Euclid,

Bailey Meter Company, a corporation ware l Ohio, assignor to of Dela- Application September 23, 1941, Serial No. 412,017

24 Claims.

This invention relates to duplicators or profilers as they are sometimes called, for machine tools, such as lathes, slotters, planers, milling machines, die sinking machines, and the like.

One object of my invention is to provide a duplicator in which the accuracy with which a work piece is shaped is unaffected by tool wear. A further object of my invention is to provide a duplicator wherein a desired contour or shape is accurately produced on a work piece regardless of misalignment between the parts or strain or wear of the parts of the machine tool.

Still another object of my invention is to provide a duplicator which may be readily'applied to a wide variety of machine tools.

A further object of my invention is to provide a duplicator wherein the tool and work piece are relatively moved from a direct comparison between the contour orshape of the master and the work piece.

Another object of my invention is to provide a duplicator wherein the linear cutting speed of the tool relative to the work is maintained constant or varied in predetermined manner.

Further objects will be apparent from the description and drawings in which:

Fig. 1 is a plan view of an engine lathe illustrating the application of my invention thereto.

Fig. 2 is a diagrammatic illustration of the control circuit employed in the embodiment of my invention shown in Fig. 1.

Fig. 3 is a modification of a part of the circuit illustrated in Fig. 2.

Fig. 4 is' an elevation view to larger size of the tracer mechanism shOWn' in Fig. 1.

Fig. 5 is an isometric illustration of the tracer mechanism shown in Fig. 4.

Fig. 6 illustrates a modified form of tracer mechanism.

Fig. '2' illustrates a modified form of my invention applied to an engine lathe and incorporating additional features. I

Fig. 8 illustrates diagrammatically a part of the control circuit employed in the embodiment of my invention shown in Fig. l.

Fig. 9 is a plan view of a milling machine illustrating the application of -my invention there- Fig. 10 is a fragmentary view to larger size of a. part of Fig. 9.

Fig. 11 is a diagrammatic illustration of the control circuits employed in the embodiment of my invention shown in Fig. 9.

As is well understood bythose familiar with the art, in some machine tools, such as lathes, the

tool is moved longitudinally and transversely of .the work piece, which except for rotation about its center remains stationary. In other machine tools, such as some types of milling machines, the work piece may be moved in two directions, while the tool except for rotation-about its axis, remains stationary. In some other types of milling machines, and usually in die sinking machines, the tool may be moved in one or more directions and the work piece also moved in one or more directions. observed, however, that it is the relative move.- ment between the tool and work piece that causes the work piece to be formed to a desired shape. As one specific embodiment I have chosen to illustrate and describe my invention incorporated in a lathe, wherein the work piece except for rotation about its center remains stationary and the tool is moved transversely and longitudinally thereof. As another specific embodiment of my invention I have illustrated my invention applied to a milling machine wherein the tool, except for rotation about its center remains stationary and the work piece is moved in two directions in order that the tool may cut the work piece to a desired shape. It will thus be evident that my invention is applicable to a wide variety of machine tools, and that when I speak of relative movement between the tool and work piece I include either an arrangement where the tool is stationary and the work piece moves, or the work piece is stationary and the tool is moved, or the combination of the two.

Certain features disclosed in this application are also disclosed in my copending applications, Serial Nos. 298,290, now Patent No. 2,259,472, issued October 21, 1941, and 384,375, filed in the United States Patent Ofllce on October 6, 1939, and March 20, 1941, respectively, of which the instant application is a continuation-in-part.

Referring to Fig. 1, I show my invention applied to an engine lathe I having a headstock 2 adapted to be rotated at desired speed by any suitable means (not shown) and a tailstock 3. A carriage .4 movable longitudinally along the bed of the lathe" in suitable ways 5 supports the tailstock 3. Also movable longitudinally along the bed of the lathe in suitable ways 6 is a carriage l. Mounted on the carriage 'l is a cross-slide 8, movable on ways 9A transversely of the bed of the lathe.

The cross-slide 8 is provided with an adjustable tool support 9 in which is secured a tool 10. Transverse movements of the tool ID are produced by means of a hydraulic servo-motor generally In all instances it will be' indicated at II supported on an extension of the carriage I and which is connected by means of a piston rod I3 to the cross-slide 8. Longitudinal movements of the tool III, that is movements of the tool parallel with the bed of the lathe, are produced by means of a hydraulic servo-motor generally indicated at I2, which as shown is secured to the bed of the lathe and connected by means of a piston rod. I4 to the carriage 1.

Supported by the headstock 2 and tailstock 3. is a work piece I5, which for illustrative purposes is shown as being formed to a parabolic shape by the tool I II. The particular shape which I have illustrated the work piece I5 as being formed to has no significance, it being apparent, as the description proceeds, that by my invention a work piece may be formed automatically to any desired contour.

In accordance with my invention, the work piece I5 is formed to any desired shape and size by continuously comparing its diameter at substantially the point it is engaged by the tool I0 with a corresponding point on a master or pattern. If such camparison indicates that a discrepancy exists between the actual size or shape of the work piece and that desired, the tool and work piece are relatively moved to remove such discrepancy. In Figs. 4 and 5 I show to larger size the form of tracer mechanism illustrated in Fig. 1 whereby I obtain a comparison between the work piece and master, and in Fig. 2 I show diagrammatically the control circuits whereby 'the tool and workpiece are relatively adjusted in accordance with such comparison. I

Referring first to Figs. 4 and 5, I therein show a master I6 clamped to a support bar I! which is secured to the bed of the lathe I. The master I6 has a profile I8 corresponding to the desired profile of the work piece I 5. It is evident that the master I6 may be shaped with any desired profile and, as will now be explained, the work piece I5 will be accurately shaped to the form and size of the master.

Engaging the profile I8 of the master is a master follower I9, which is shown in the form of a horizontal projection of a vertical slide 20 held in position by suitable ways in the carriage I. The slide 20 and accordingly the master follower I9 are positioned longitudinally along the lathe with the carriage 1. The slide 20 will however be positioned vertically relative to the carriage I in accordance with changes in shape of the master I6.

Pivoted to the master follower I9 is a bell crank 2I having a horizontal arm forming a work follower 22, which engages the work piece I5, and a vertical arm 23 forming a baffle or valve plate for nozzles 24 and 25-, the latter being adjustably i m d on a support 26 secured to the slide 20. ill; will be observed that so long as the master follower I 9 and work follower 22 move up or down in unison, the baffle 23 will not shift relative to thenozzles 24 and 25. When, however, there is a rise in the profile of the master I6, the bafile 23 will be positioned in a clockwise direction. thereby moving toward the nozzles 24 and 25. Conversely when there is a fall or depression in the master I6 the baille 23 will be positioned in a counterclockwise direction, thereby moving away from the nozzles 24 and 25. Similarly, if the diameter of the work piece I5 increases, causing the work follower 22 to move upwardly, the baffle 23 will move away from the nozzles 24 and 25, whereas a decrease in diameter of the work piece I5 will cause the work follower 22 to be positioned downwardly and the baflle 23 to move toward the nozzles 24 and 25. A spring 2IA may be provided for urging the bell crank 2| in a clockwise direction so that the work follower 22 is urged against the work piece I 5.

The master follower I9, work follower 22, and tool III are in the same plane at right angles to the axis of the work piece I5, so that it may be said that the tracer mechanism in efiect compares the shape or size of the work piece I5 immediately after being formed by the tool III to that of the master I6 and causes the baffle 23 to be positioned relative to the nozzles 24 and 25 in accordance with any discrepancy therebetween. Or again it may be said that the tracer mechanism simultaneously scans the master I6 and work piece I5 and moves the bafil'23 relative to the nozzles 24 and 25 in accordance with any discrepancy between the two shapes. By means new to be described movements of the baflle 23 toward or away from the nozzles 24 and 25 control the movements of the tool I 0 so that the work piece I5 is shaped to correspond to the shape of the master I6.

Referring now to'Fig. 2, I show in diagrammatic fashion the tracer mechanism and the control circuits whereby movements of the baflle 23 relative to the nozzles 24 and 25 position the tool I0 relative to the work piece I5. The nozzles 24 and 25 are supplied witha suitable fluid under pressure, such as compressed air, from any suittable source (not shown) and continuously discharge the pressure fluid to the atmosphere in the form of jets against the baflie 23. Pressure fluid for the nozzles 24 and 25 first passes through a shutoff valve 30, a reducing valve 3|, and a stabilizing volume tank 32. Pressure fluid for the nozzle 24 is transmitted through a pipe 33 in which is an orifice or other suitable restric- 40 tion 34, and that for the nozzle 25 through a pipe in which is an orifice 36.

Movements of the baille 23 toward the nozzles 24 and 25 cause proportional decreases in the discharge of pressure fluid therefrom, thereby causing an increase in pressure in the sections of pipes 33 and 35 between the orifices 34, 36 and nozzles 24, 25 respectively. Conversely, movements of the baflle 23 away from the nozzles 24 and 25 cause proportionate increases in the discharge of pressure fiuid therefrom, thereby decreasing the pressure within the sections of pipes 33 and 35 beyond orifices 34 and 36. For each particular distance between the baffle 23 and nozzles 24 and 25 a predetermined pressure will exist within the sections of pipes 33 and 35 beyond orifices 34 and 36. When proper correspondence exists between the contours of the work piece I5 and master I6 a definite pressure which for convenience I call the "normal pressure will exist in the sections of pipes 33, 35 beyond orifices 34, 36. This normal pressure may be brought to a desired value by moving the nozzles 24 and 25 toward or away from the bafile 23 by the adjustments provided. comprising nuts 24A and 25A (Figs. 4 and 5). In the embodiment of my invention now being described, the arrangement is such that when normal pressure exists the servo-motor II governing transverse movements of the tool In remains stationary, whereas the servo-motor I2 governing longitudinal movements of the carriage I is operated at maximumspeed.

The servo-motor I I is shown in diagrammatic fashion in Fig. 2 and comprises a power unit for positioning the cross-slide 8 in one direction when the pressure established by nozzle 24 and baflle 23 is above the normal value, and in opposite direction when the pressure is below the normal value. The speed with which the cross-slide is positioned will depend upon the amount of departure of the pressure from the normal value. The servo-motor It includes a reservoir 36A for a hydraulic fluid such'as" oil, in which is disposed a pump 31 driven by a suitable motor 31A. The pump 31 draws oil from the reservoir and discharges it into the inlet port 39 of a pilot valve 38. A suitable relief valve 33A may be provided to maintain the discharge pressure from the pump 31 below a predetermined value. The pilot valve 38 has a movable valve stem 38A connected at its .upper end to the movable head of an expansible bellows 40 connected to the pipe 33 beyond the orifice 34. Upon an increase in pressure within the pipe 33 the bellows Ml will expand, causingthe valve member 33A to move downwardly. Conversely, upon a decrease in pressure within the pipe 33 the bellows. 40 will contract, causing the movable valve member 38A to move upwardly.

In my earlier filed copending applications Serial Nos. 298,290 and 384.375. to whch reference has previously been made, I disclose in detail the servo-motor II and particularly the pilot valve 38. Suificient it is to state here that the valve member 38A has a mid or neutralposition when there is no communication or such communication between the inlet port 39 and outlet ports 42 and 43 that the forces acting on opposite sides of a piston 35 are equal. Upon downward movement of the valve member 38A from the neutral position the outlet port 52 is placed in communication with the inlet port 39 and the outlet port 43 in ccmmunicaton with an exhaust port 45. Upon Upward movement of the valve member 38A from the neutral position the outlet port 33 is placed in communication with the inlet port 39,

and the outlet port 42 in communication wlththe exhaust port 45.

The outlet ports 42. and 43 means of pipes 46 and 41 to a cylinder 48 on oppo site sides of the piston 35 driving the piston rod l3. When normal pres-sue exists within pipe 33 the movable valve member 38A is in the neutral position, so that the pston 35 remains stationary. When the pressure within pipe 33 increases above the normal value however,-causing the valve member 38A to move downwardly, oil under pressure will be transmitted through pipe 46 to the upper s'de of the piston 35 as viewed in Fig. 2,

thereby caus ng the piston to move downwardly.

Oil from the lower side of piston 35-will be transmitted th' oi'gh pipe 41 and pilot valve 38 to the oil reservoir 35A. A decrease in pressure within pipe 33 will cause a movement of the piston 35 in opposite direction.

Assuming for example that due to wear of the 'tool to the workpiece increases sl'ghtly in diameter. the pressure within the pipe 33 will decrease because of the movement of the bafiie 23 away from the nozzle 24. 'Oil under pressu c will then pass from the pump 31 to the lower side of the piston 35, causing the cross-slide 8 tobe positioned in a direct on to move the tool H3 toward the work piece l5. Such movement pf he tool It! will continueuntil the pressure within pipe 33 is restored to the normal value. Upon a rise in the master IS the master follower 13 will move upwardly, causing the baflle 23 to approach the nozzle 24, increasing the pressure within pipe 33 and causing valve member 38A to move downwardly from the neutral position.

are connected by Oil under pressure will then pass from the pump 31 to the upper side of the piston 35, causing the tool ill to be moved away from the work. As'the diameter of the work piece l5 increases, the work follower 22 will be moved upwardly, and when the increase in diameter of the work piece I5 corresponds to the rise of the master IS, the baflle' 23 will be restored to the normal position,

and the valve member 38A to the neutral position.

When the shape of the work piece I5 corresponds to that of themaster IS the tool l0, as

will be appreciated by those familiar with the art.

may be movedlongitudinally along the lathe at a relatively high speed. However, when a transverse movement of the tool 10 is required, it is desirable that the longitudinal speed of the carriage along the lathe be decreased. The decrease in longitudinal speed is preferably proportional to the 'taper desired on the work piece, and if the work piece is to be formed with a shoulder at r'ght angles to its axis, then the carriage is pref erablystopped until the required transverse movement of the tool is completed. That such operation is desirable will be appreciated from a consideration of the fact that the absolute movement of the tool Ill relative to the work piece I5 is determined by the component of its motion in a direction transverse to the longitudinal axis of the lathe. and its motion parallel to the axis of the lathe. Accordingly, if it is desired that a shoulder, for example, be formed on the work piece 45, longitudinal movement of the tool Ill should be stopped during the period of time that it is being moved transversely. Accordingly, I combine with the transverse control of the tool Ill, which I have described, a control of the longitudinal movement of the tool l0, which I will now describe.

Again referring to Fig. 2 it will be observed that the pressure within that portion of the pipe 35 beyond the orifice 36 changes in correspondence with changes in the pressure within the pipe 33 beyond the orifice 34, and that when the normal distance exists between the battle 23 and nozzles '24 and 25 a predetermined normal pressure will ex st within the pipe 35. The

pressure within the pipe 35 controls the operation of the servo-motor l2, and accordingly the rate at which the tool In is moved longitudinally along the lathe. When normal pressure exists within the pipe 35 the tool I8 is moved longitudinally along the lathe at a desired maximum speed, and upon an increase or decrease in pressure from thenormal, the longitudinal rate of movement of the tool In is decreased, and at a predetermined minimum or maximum pressure the longitudinal movement of the-tool I0 is stopped. The servo-motor l2 for operating the carriage 1, upon which the tool In is mounted-is in general similar to the servomotor II and includes an oil reservoir 5! in' which is disposed an oil pump 52 driven by a motor 53. The pump 52 is connected by way of a pipe 5l,-4-way valve 55, and pipe 56, to a cylinder 51 on one side of a piston 58 driving normal pressure exists within pipe 35, the fluid res stance 63 is at a minimum, so that the piston 53 and accordingly the connected piston rod I4 is positioned to the right as shown in Fig. 2

' longitudinal movement of the carriage 1.

In my earlier filed copending application, Serial No. 384,375, previously referred to, I disclose in detail the fluid resistance 63. In general, it may be said that it is provided with a movable member 64 vertically positioned as shown in Fig. 2 by means of an expansible bellows 65, which is connected to the pipe 35 between orifice 36 and nozzle 25. Movements of the valve member 64 upwardly or downwardly from a neutral position by virtue of the expansion or contraction of the bellows 65, effect increases in fluid resistance. A suitable adjusting means, as shown at 61A, may be provided whereby the resistance to fluid flow existing when normal pressure exists within the bellows 65 may be varied so that normally the carriage 1 will move longitudinally along the lathe at a desired maximum speed.

The control system shown in Fig. 2 may be provided with various safety and other devices for' facilitating operation. Thus I show connected in the power supply to motors 53 and 31A an air pressure failure switch 61 which prevents their operation unless air pressure is availablefor the nozzles 24 and 25. Also shown connected in circuit with motor 53 are limit switches 68 and 69 arranged to .be operated by a projection 18 carried by the piston rod M. The switches may be adjusted so that upon the tool reaching either end of the master l6 motor 53 is deenergized, thereby preventingfurther travel of the carriage which might result in damage to the tool or other parts of the lathe. A push button station ll allows the operator to reenergize motor 53 after the power supply thereto is broken, either at' switch 68 or 69. Also connected in circuit with motors 31A and 53 are manually operable switches 12 and 13 respectively, which afford the operator instantaneous control over the transverse or longitudinal feed of the tool It).

As shown in Fig. 1, the tool I is arranged to traverse the work piece from left to right. Upon the tool reaching the end of the work piece motor 53 will be deenergized as heretofore described by switch 69 opening. The tool I0 can then be moved transversely away from the work piece l5 by the baflie 23 being manually moved relative to the nozzle 24. In order that the tool It may be returned to the left end of its travel I provide a hand operable lever 15 for simultaneously operating the-4-way valve 55 and the 3-way valve 69. Thus upon the tool In reaching the right end of its travel the switch 69 will open, deenergizing motor 53. The operator will then relatively move bafiie 23 and nozzle 24 so that the tool is positioned away, from the work. Lever 15 would then be shifted from stop 16 to a stop 11 and the circuit to motor 53 would be closed by means of push button station 1|. Shifting of lever 15, as shown in Fig. 2, connects pipe 59 to the supply pipe 54 and pipe to a waste pipe 18 through the 3-way valve 60. Thus supply pressure will be effective on the righthand side of piston 58, whereas the pressure on. the left-hand side of piston 58 will be released. The carriage will then be positioned at a rapid rate to its initial starting position.

. the 3-way valve 60. Fluid exhausted from the cylinder 51 during the working stroke of the piston 58 passes through the 4-way valve 55 and is exhausted into the oil reservoir 5! through a relief valve 80, which serves to maintain a predetermined pressure of relatively small magnitude in the exhaust line.

As heretofore described, when the movable member 64 of the fluid resistance 63 is in the mid position the resistance is at a. minimum and increases upon the member 64 being positioned upwardly or downwardly. It is highly desirable that when the member 64 is in an extreme upper or lower position that the piston 58 remain stationary, as it is this condition which obtains when the master calls for a cut to be made at right angles to the center line of the work piece, and any motion of the piston 58 would cause inaccuracies. In order thatany leakage through the resistance 63 when the member 64 is in a position calling for maximum resistance will not produce motion of the piston 58 I connect the outlet of the fluid resistance 63 to the exhaust line leading to the relief valve 88 through a bleed valve 8I. The bleed valve 8| may be adjusted so that when the resistance. 63 is at a maximum the piston 58, and accordingly the carriage I, will be stationary.

It will be observed that except for this distinction the operation of the control system shown in Fig. 3 is the same as that illustrated in Fig. 2. During the working stroke of the piston 58 the lever 15 is in the. position shown. so that fluid pressure from the pump 52 after passing through the fluid resistance 63 is. admitted to the cylinder 51 on the left-hand side of the piston 58, thereby causing it to move at a rate varying with changes in the fluid resistance. A rapid traverse at the end of the working stroke is made by moving the lever 15 from the stop 16 to the stop 11 which connects the cylinder 51 on the right-hand side of piston 58 to the pump 52, and on the left-hand side to the relief valve through the 3-way valve 60.

In Fig. 6 I show a modified form of a tracer mechanism especially preferable for-heav'y work where the cutting operation imposes a heavy load on the machine tool. The elements of the tracer mechanism are so supported and constructed as to accurately shape the work piece notwithstanding the machine tool may be under heavy stress and strain. The mechanism also shapes the work piece accurately regardless of tool wear.

Referring to Fig. 6, a V-block 90 is reciprocable along a way 9| secured tothe cross-slide 8. The V-block is urged against the work piece 15 by means of a spring 92-. As the work piece I5 decreases in diameter the V-block 90 under the influence of the spring 92 will move to the right as viewed in the drawings, and when the workpiece increases in diameter will move to the left. Disposed in the center of the V is a plunger 93 urged against the work piece l5 by a leaf spring 94, which urges baffle 95 about pivot 96 in a counterclockwise direction against the plunger. Pivot 96 is carried by a master feeler 91 movably supported on the V-block 98 in a way 98. Assuming that the master feeler 91 remains stationary it will be evident that if the'diameter of the work piece I increases, causing the V-block 99 to be positioned to the left, the plunger 93 will move to the right relative to the v-block, due to the action of the spring 94 against the bailie 95. Conversely if the work piece I5 decreases in diameter, then the V-block 90 will move to the right, causing the plunger 93 to.

move to the left relative to it and effecting a clockwise positioning of the baflie 95 pivot 96 against the action of spring 94. I From the foregoing it-will be observed, assuming that the master feeler 91 remains stationary, that a change in diameter of the work piece I5 causes a corresponding positioning of the bafile 95, such positioning being in a clockwise direction about the pivot 96 upon a decrease in diameter of the work piece I5 and in a counterclockwise direction upon an increase in diameter.

Nozzles 24 and 25 are adjustably secured to an upright member 90A secured to the V-block 99. As the baffle 95 is positioned in a clockwise or counterclockwise direction it approaches and recedes from the nozzles. Such positioning toward and away from the nozzles, as heretofore described, controls the pressure within the nozzles and through the control system illustrated in Fig. 2 and previously described, the longitudinal and transverse movements of the tool I0. Thus upon. an increase in diameter of the work piece I5 the plunger 93 willbe moved to the right relative to the V-block 90, causing the bafile 95 to move away from the nozzles 24 and 25. Such. movement will effect a decrease in pressure within the nozzles 24 and 25 causing the tool III to be positioned to the left, as viewed in Fig. and simultaneously to decrease the rate of movement of the carriage 1 along the lathe. When the diameter of the work piece has been restored to that desired, the movement of the tool III to the left will cease and the movement of the carriage 1 longitudinally along the lathe will increase to the optimum value. Upon a decrease in diameter of the work piece I5 the plunger 93 will be positioned to the left relative to the V-block 99, causing the baiile 95 to approach the nozzles 24 and 25, causing an increase in pressure therein. Such increase in pressure will cause the tool III to be positioned to the right, as shown in the drawings, and simultaneously to decreasethe speed with which the carriage 1 is positioned longitudinally along the lathe. When the diameter of the work piece I5 has been restored to that previously existing the transverse movement of the tool ID will cease and that of the carriage will be restored to optimum speed.

In the operation just described it has been assumed that it was, wished to shape the work piece l5 to a cylinder. I will now describe the means whereby the work piece may be shaped as desired in accordance with a master, such as the master 16A shown in Fig. '6. Referring to Fig. 6, secured to the lathe at a point adjacent the tailstock is a vertical support member 99 having a horizontal extension I99. A similar support adjacent the headstock is not shown in Fig. 6. Carried by the supports adjacent. the head and tailstocks is a horizontal bar I91 provided at either end with an extension I02 having a slot I93 in which is disposeda pin I04 fastened to the horizontal extensions I99 of the supports 99. The bar II" is therefore free to move trans 'versely of the lathe by virtue of the slot and pin construction but not longitudinally thereof. The bar IIII is shaped to form, a support for the about the 7 profile of the work piece I5 with that of the master ISA, which is clamped to the former by means of clamps, such as shown at I05. Sup- ?ported by and secured to the V-block is a post I01.

work piece I5 engaged by the 000] Hi. It will be observed that so long as the profile of the master IBA is parallel to the axis of the lathe I and work piece I5, the master feeler 91 will remain stationary relative to the V-block 99: While this. condition obtains the bafile will be moved toward or away from the nozzles 24 and 25 solely because of changes in. the shape of the work piece I5. A change in the profile of the master IGA will however cause the master feeler 91 to.

move relative to the V-block 90. Such movement will cause the baflie 95 to approach or recede from the nozzles 24 and 25. The change in pressure within the nozzles will then, as previously described, affect the transverse and longitudinal movements of the tool I9, so that the profile of the work piece I5 will be brought into correspondence with that of the master ISA. Thus upon a rise in the profile of the master IGA, causing the master feeler 91 to be positioned to the right as shown in the drawings relative to the V-block 99, the baffle 95 will be positioned toward the nozzles 24 and 25. Such positioning will cause the tool III to be positioned to the right, and hence duplicate upon the work piece I5the rise or projection on the master IBA. Conversely upon'a tions of the baffle 94 and nozzles 24 and 25 will be restored to that existing prior to the change, and, thereafter no further motion of the tool IIi 111 a transverse direction will occur unless there is a further change in the shape of the master, or in the shape of the work piece. It will be observed that by virtue of the fact that all of the elements comprising the tracer mechanism are supported by or operated from the V-block 90, strains in the parts of the machine tool will have no effect upon the accuracy of the mechanism, but that the mechanism directly compares the master ISA, and causes the tool II) to be positioned in proper direction until desired correspondence is restored.

In order that chips formed in the cutting operav tion may be quickly removed so that accurate positioning of the V-block- 90 will not be interfered with, a suitable air jet II I may be provided to blow the chips away from the V-block.

In Fig. '1 I show a further embodiment of my invention incorporating additional features. It is well appreciated that for optimum results the linear speed of the tool relative to the work piece should remain supstantially constant or be varied in a predetermined manner. That is to say, there is an optimum speed with which the work is moved past the tool, or vice versa.' In cutting operations,

--particularly turning operations, the linear speed of the work piece past the tool decreases as the tool approaches the center of rotation of the work piece, it the headstock is rotated at constant speed. Thus unless the turning operation is interrupted and the rotary speed of the headstock varied as the diameter of the work piece varies the turning operation will not be performed at maximum efficiency. It is particularly desirable that the speed of the headstock be automatically varied in accordance with changes in diameter of the work piece when the tool is automatically positioned relative to the work by a master, as such automatic operation dispenses entirely with the necessity of an operator devoting his atten-.

inafter the speed of the work piece past the tool is preferably varied in predetermined fashion.

Referring to Fig. 7, I therein show the lathe I wherein the tool I0 is automatically positioned transversely of the work piece I5, a well as l0ngitudinally thereof, in accordance with changes in the shape of the master I6. Additionally thereto I further show in Fig. '7 apparatus whereby the work piece I5 is rotated at a variable speed depending upon the radial position of the tool I0. My invention contemplates that the speed with which the work piece I5 is rotated may be varied in any predetermined desired manner. Generally, however, it is thought preferable to have the work piece [5 rotate at an increasin speed as the tool I0 approaches the center of rotation.

Referring to Fig. 7, I show the headstock 2 rotated by a hydraulic motor I20 through gears I2IA and I:22A. In Fig. 8 I show diagrammatically the fluid control circuit for the hydraulic motor I20. In general, it will be observed that the control circuits are similar to those illustrated in Fig. 3 for the servo-motor I2. Hydraulic fluid under pressure is transmitted to the motor I20 through a pipe I2I connected to the outlet of a. variable fluid resistance I22 which is supplied with-hydraulic fluid from a suitable pump I23 driven by a motor I24. The pum I23 and fluid resistance I 22 are for convenience housed in an hydraulic fluid reservoir I25 and the hydraulic fluid discharged from the motor I20 is returned thereto through a pipe I2 IB.

As described with reference to the fluid resist ance 63, shown in Fig. 2, the fluid resistance I22 at some position of the movable member I26 has a minimum resistance at which position the flow of oil to the motor I20 will be at maximum, and accordingly the headstock 2 will rotate at maximum speed. If the member I26 is positioned upwardly or downwardly from this position the fluid resistance I22 will increase, thereby causing the motor I20and headstock 2 to rotate at a slower speed.

The position of the member I26 is controlled by an expansible bellows I21 connected through a pipe I28 and 3-way valve I29 to a nozzle I30 carried by the movable carriage I. Air under pressure is supplied the pipe I28 through an orifice I3l.- As described with reference to the operation of the nozzles 24 and 25, as the rate of discharge through the nozzle I30 decreases, the pressure within the pipe I23 will increase, thereby causing the bellows I21 to position the member I26 downwardly. Conversely upon an increase in the rate of discharge from the nozzle I30 the bellows I21 will contract, causing the member I26 to move upwardly, causing a corresponding change in the resistance of the fluid resistance I22.

The rate of discharge through the nozzle I30 is controlled by means of a cam I32 secured to .the cross-slide 0. The cam I32 may'be given any shape desired, so that the magnitude of the fluid resistance I22, and accordingly the speed of the motor I20 and headstock 2 will be varied as desired. For reasons heretofore stated it is usually preferable to have the rotative speed of the work piece I5 increase as the tool I0 is positioned toward the center thereof. Accordingly,-

ever to produce a desired functional relation be- 1 tween the transverse positioning of the tool I0 and speed of rotation of the work piece I5.

In order that the fluid motor I20 may be manually operated at any desired speed, I provide the three-way valve I29, which in the position shown places the bellows I21 under the control of the nozzle I 30. When the three-way valve I 29 is shifted from the stop I33 to a stop I34 the nozzle I30 is shut off from the bellows I21 and' a pipe I35 connected thereto which may be supplied with compressed air from any suitable source. Located in the pipe I35 is a control valve I36. The pressure within the bellows I21 and accordingly the speed of the hydraulic motor I20 and headstock 2 may be varied by manipulation of the valve I36, increasing or decreasing the pressure within the pipe I28. I show between the valve I36 and the three-way valve I29 a bleed port I31 open to the atmosphere, which permits a flow of pressure fluid through the valve I36, and accordingly it is evident that positioning of the valve I36 will produce corresponding variations in pressure within the pipe I28 and bellows I21.

It is apparent that any suitable tracer mechanism, such as illustrated in Figs. 4, 5 or 6, may' be employed in the embodiment of my invention shown in Fig. 7. I have for clarity diagrammatically shown such a mechanism wherein the nozzles 24 and 25 are carried by a horizontal bar supported on the cross-slide 0 and the masterfeeler is carried by a substantially parallel horizontal baflie pivotally supported on the carriage 1 and urged against the shaped profile of the master I6 bysuitable spring means. In operation, movements of the baflle toward or away from the nozzles 24 and 25 effect desired longitudi nal movements of the carriage 1 and transverse movements of the cross-slide 0 as heretofore described.

In Figs. 9, 10 and 11 I illustrate the application of my invention to a vertical milling machine, such as shown in my earlier filed copending applications Serial Nos. 298,290 and 384,315. In Fig. 9 I show in sectional plan view so much of a vertical milling machine as is necessary for an understanding of my invention. The milling machine has a vertical column I40 for supporting a knee I4I which is vertically movable along the column I40 in ways I42 formedon the column. The knee I is provided with ways I43 along which a saddle (not shown) is movable toward and away from the column I40. The said saddle supports a work table I44 on suitable ways so that the latter is movable to the left and right as shown in the drawings by means of a servo-motor generally indicated at I45.

At I46 is shown a typical work piece consisting of a concave forging of more or less elliptical shape, and in rough form having a raised blank face extending around its entire periphery. The

machining operation I have chosen to illustrate my invention as controlling consists in forming a male flange on this blank face. A cutter I41 is rotated by any suitable means (not shown) and engages the work piece I46. It is the pu1- pose of my invention to so control the relative movement between the work piece I46 and cutter I41 that the former will be accurately formed to a desired profile.

The work piece I46 is shown as being secured to a fixture I48 by adjustable clamping means I49. Because of the nature of the machining operation to be performed the fixture 'I48 is mounted on a circular table I50, shown more clearly in Fig. 10, secured to the work table I44 and rotated at desired speed by a hydraulic motor II. In Fig. 9 I have shown the operative connections between the motor I5I and table I50 in diagrammatic form, it being evident that suitable reducing gears, universal joints, etc. m'ay be employed as necessary. It is sufficient for the purpose of illustrating my invention to state that the table I50 is rotated at a speed corresponding with the rate of rotation of the motor I5I. Machining of the work piece I46 is completed in one revolution of the circular table I50. During the revolution the-work piece I50 is moved relative to the cutter I41 and the rate of rotation of the work piece I46 varied so that the cutter I41 accurately profiles the male flange and the work piece.

The fixture I48 has a horizontally extending skirt I52 forming a cam or template which by means now to be described controls the relative movement betweenthe tool and work piece so that the raised flange on the latter is properly formed. The skirt I52 is preferably provided with a raised barrier I52A to hold chips cut from the work piece from scattering.

Secured to the knee MI is an arm I53 which carries a nozzle I54. The arm I53 also pivotally supports a follower I55 having a Projection I56 urged by a spring I56A against the cam I52. As the circular table I50 rotates, changes in the shape of the pattern I52 will cause the follower I55 to be positioned toward or away from the nozzle I54.

The nozzle I54 is supplied with a suitable fluid under pressure, such as compressed air, from any ,suitable source (not shown) through a shutoff valve I51, a pressure regulating valve I56, a volume tank I59, an orifice I60 and pipe I6I. As described with reference to the embodiment of my invention illustrated in Fig. 1, for example, as the follower I55 approaches the nozzle I54, the pressure in pipe I6I between the orifice I60 and nozzle I54 will increase, whereas movements of the follower I55 away from the nozzle I54 will effect corresponding decreases in pressure within the pipe I6I. I

Variations in pressure within the pipe I6I control the operation of the servo-motor I45. Re-

wardl'y, causing the servo-motor the work table I44 accordingly. Thus, for excircuits therefor, including vierring toFig. 11, it will be observed that the pipe I6I connects to a bellows I63 through a pipe I64. Movements of the bellows I63 control the operation of a pilot valve I65 supplied with hydraulic fluid from a pump I66 driven by a motor I6'I. So long as a normal distance exists between the nozzle I54 and the follower I55, the movable member I68 of the pilot valve I65 is in the neutral position and the servo-motor I45 remains stationary. When, however, the follower I55 approaches toward or recedes from the nozzle I54 the member I68 is positioned downwardly or up- I45 to position ample, assuming the -follower I55 to be positioned away from the nozzle I54 by virtue of a change in the contour of the pattern I52, the servo-motor I45 will position the work table I44 in such a direction as to restore the follower I55 toits original position relative to the nozzle I54. In the embodiment of my invention illustrated in Fig. 9, upon the follower I55 being positioned in a counterclockwise direction, thereby moving away from the nozzle I54, the servo-motor I45 will operate to position the work table I44 to the left as viewed in the drawings until normal distance is restored between the follower I55 and nozzle I54. It is apparent thatby proper shaping of the pattern I52 any desired contour may be cut on the work piece I46.

As shown in Fig. 9, and as illustrated in the embodiments of my invention heretofore described, the servo-motor I45 and the hydraulic the pilot valve I65, pump I66, and electric motor I61, are preferably arranged in a unit which may be conveniently mounted relative to the milling machine. Likewise suitable control and protectiye devices may be provided. Thus I show in the electric circuit to the motor I61 a fluid pressure responsive switch I69 adapted to open the circuit to the motor I61 upon failure of fluid pressure. Likewise I show in the circuit to the motor I61 a push button station I10, so that the operation thereof may be started and stopped by an operator.

If the circular table I50 rotates at constant speed, because of the non-circular contour desired on the work piece I46 the relative movement between it and the tool I41 will vary greatly. As will be readily appreciated by those familiar with the art, the uneven feeding resulting from such non-uniform movement will result in an uneven surface on the work piece I46 in those portions where the relative rate of movement between tool and work piece is not at the optimum. Ac cordingly, my invention contemplates varying the speed of the circular table I50 in accordance with contour of the work piece I46, so that the latter is always moved relative to the tool I41 at an optimum rate of speed. To accomplish this result I show the hydraulic motor I5I under the control of a control couple comprising a nozzle HI and follower I12, the latter being provided with a projection I13 urged by a spring I13A against a cam I15 secured to the table I50. The nozzle III is mounted on the work table I44. The follower I12 is pivotally mounted at I16 to the work table. It will be evident that so long as the cam I15 is circular there will be nochange in the distance between the follower I12 and the nozzle "I. A change in radius of the cam I15 will, however, cause the baflie I12 to move toward zle I54, through an orifice or other restriction I11. Movements of the follower I12 toward or away from the nozzle I1I cause corresponding variations in pressure within the nozzle I1I, which are transmitted through a pipe I18to a control unit generally indicated at I19. The control unit I19 is similar to the unit illustrated in Fig. 8. and controls the flow of hydraulic fluid to and from the hydraulic motor I5I in accord ance with the pressure of the fluid within pipe I18. As explained with reference to the control unit shown in Fig. 8, at one value of pressure the control unit I19 is so arranged that a maximum flow of hydraulic fluid to the motor I5I will be established. .As the pressure within pipe I18 increases or decreases from this value, the control unit I19 will act to proportionatelydecrease the flow of hydraulic fluid to the motor I SI, thereby decreasing the rate of speed of the circular table I50.

The cam I15 may be shaped so that when the tool I41 and work piece I46 are relatively moved at maximum speed the battle I12 is a normal distance from the nozzle HI, and that when the desired shape of the work piece I 46 is such that the relative speed between it and the tool I41 is desirably decreased, the radius of the cam I 15 is either increased or decreased. By varying or shaping the cam to different radii at different points it is evident that the relative rate of movement between the tool I 41 and work piece I46 may be varied as desired.

In Fig. 11 I have shown the control unit I19 diagrammatically and it comprises an adjustable fluid resistance I80 supplied with hydraulic fluid from a pump I 8| driven by a motor I82. A bellows I 8'3, to which pipe I18 is connected, positions the movable member of the fluid resistance I88 in accordance with variations in the shape of the cam or pattern I15.

, Operation of the motor I82 may be controlled by a suitable switch I90. Also to stop or prevent operation of the motor I82 upon failure of air pressure the switch I69 may be, as shown, connected in circuit with the motor I82.

Throughout the foregoing specification and in the claims to follow I have indicated that the work piece is formed to correspond to the profile or shape of the master. By such language I do not intend toimply that the work piece is brought to the exact shape of the master, but as will be evident to those'familiar with the art the master will be formed so that the ultimate shape of the work iece produced is that desired, and that therefore theshape of the work piece will difier from that of the master by the amount of angularity, etc. in the mechanism. Furthermore, I use the terms contour, profile, shape, and the like, in a broad sense and not with any limiting distinction between the profile of a two-dimensional silhouette or the surface configuration of a body, for example.

Certain portions of my invention, disclosed but not claimed herein, are disclosed and claimed in my copending divisional application Serial No. 474,273, and in my continuation-in-part application Serial No. 524,707.

What I claim as new, and desire to secure by Letters Patent of the United States, is:

1. In a duplicator for machine tools and the like having a relatively movable tool and work piece, a pattern having a shape corresponding tothe desired shape of the work piece, means for comparing the shape of the work piece to that of the pattern, and power means under the having a relatively movable tool and work piece,

control of said means for comparing the shape of the work piece for relatively moving said tool and work piece.

'2. In a duplicator for machine tools and the like having a relatively movable tool and work piece, a pattern having a shape corresponding to the desired shape of thework piece, means for comparing the shape of the work piece with that of the pattern, and power means for relatively moving said tool and work piece to maintain correspondence between the shape of the pattern and that of the work piece.

3. A duplicator for machine tools and the like comprising in combination, a pattern having a shape corresponding to the desired shape of the work piece, a difierential mechanism having a first part positioned in correspondence with changes in the shape of the pattern, a second part positioned incorrespondence with changes in the shape of the work piece, a third part operated by said first two named parts positioned in accordance with changes in the relative positions of said first two named parts, and means under the control of said third part for relatively positioning said tool and work piece.

4. A duplicator for machine tools and the like having a relatively movable tool and work piece,

comprising in combination, a pattern having a shape corresponding to the desired shape of the work piece, a first member engaging said pattern and positioned in accordance with changes in the shape thereof, a second member engaging said work piece and positioned in accordance with changes in the shape thereof, and means under the joint control of said members for relatively moving said tool and work piece. I

5. A duplicator for machine tools and the like having a relatively movable tool and work piece, means for relatively moving the tool and work piece in one direction to cause the tool to traverse the work piece, and. means for moving said tool in a direction transverse to said first direction, comprising, a first element traversing a pattern as the tool traverses the work piece, a second element traversing the work piece as the tool traverses the work piece, and means under the joint I control of said elements for positioning the tool relative to the work piece in the second direction. -6. A duplicator for machine tools and the like having. a relatively movable tool and work piece,

means responsive to changes in the shape of a pattern for causing said tool to move relative to the work piece, and follow-up means responsive to changes in the shape of the work piece for stopping said relative movement when the shape of the work piece corresponds to that of the pattern.

7. A duplicator for machine tools and the like having a tool and work piece relatively movable alon two paths, a pattern, a. control couple for governing the relative movement of the tool and work piece along both said paths, and means under the joint control of the pattern and work piece for relatively moving the elements of said couple.

8. A tracer mechanism for a machine tool having a relatively movable work piece and tool, comprising in combination, a pattern having a shape corresponding to the desired shape of the work piece, a first member linearly moved in accordance with changes in the shape of said pattern, a second member pivotally mounted on said first member and engaging said work piece, and means for controlling the relative movements of the tool and-work piece inaccor'dancawith. the displacement of said second member fromea. predeterminndipositiona 9. LA tracer mechanism for a machine tool having a relatively --movable work piece and tool, comprising in. combination, a. pattern having a shape corresponding-to the desired shape .of the work piepe aflifierential member positioned. in accordance .withchangesin the relative shapes of the pattenn and-work piece, meansfor causing said member. to .trav erse -thehpattern and work piece as l the tool traversesthe workpiecenand means under the controLof said member 'for controlling relative movements, between. the tool and workpiece s. v

10. In a metal forming machine, a.-tol andia supp therefor actuatedby the. machine and causing the toolto perform a cutting operation,

' means by .which the .tool is caused. to traverse a predetermined-Path to. form the work corresponding to the-form, oi a pattern, comprisin a 3 actuating, element, I a. differential member arranged totraverse' the pattern and work as the tool is caused to traverse the work, and means whereby -displacements of said member from a predeterminedposition.gause said tool actuating element to relatively move said tool and work piece.

11. In combination with a lathe having a movable carriage and a tool mounted thereon, a pattern mounted on said lathe having a contour corresponding to the desired contour of a work piece,

a. member movable with said carriage and scan-' ning said pattern, a bell crank pivotally mounted on said member and having an arm scanning the work piece, and means responsive to relative movements of said member and bell crank for moving said tool relative to said carriage.

12. In a duplicator for machine tools and the like having a relatively movable tool and work piece, means in constant contact with said work piece and positioned in accordance with changes in the shape of the work piece, a member supported by said positioned means and adapted to be moved relative thereto in accordance with changes in the shape of the work piece, and additional means under the control of said member for relatively positioning the tool and work piece.

13. In a, duplicator for machine tools and the like having a relatively movable tool andwork piece, a gaging device in constant contact with said work piece and having relatively movable parts positioned in accordance with changes in the diameter of the work piece, a control couple mounted on said gaging device and having relatively movable elements positioned in accordance with relative movements of said first named parts, and means under the control of said couple for relatively moving said tool and work piece.

14. In a duplicator for machine tools and the like having a relativelymovable tool and work piece, a gaging device comprising a, V-block the sloping sides of which are in engagement with the work piece, a plunger supported in said V- block and the center line of which bisects the angle of the V and engages the work piece so that the plunger moves relative to the V-block in accordance with changes in the diameter of the work piece, a control couple having relatively movable elements supported on aid v-block and an operative connection between said plunger andone of the elements of said control couple so that a control eflfect is produced corresponding block, and means .for relatively positioningthe tool and work piece under the control of [said control eiiect.

15. Ina. duplicator for machine tools, and the like having a relatively movable tool. andwork piece, a gaging device mounted on saidduplicator. comprising a V-block, the sloping sides of which are in constant engagement with the work piece so that the work pieceapproaches and re- .cedes. from the apex of the.v. as the diameter of the work piece decreases and-increases, means fondetermining the distance fromthe apeieto the surface of the work piece,.and..continuously operated means understhecontrol of said-last named means for relatively moving said toolcand work piece in accordance with the said. contimuously operated means. y

16. In a duplicator for machine. toolsand the like having a relatively movable tool and work piece,.a gaging device comprising. a base-part. in engagement. with the work piece-anda-phmger supported in said base part. and movable. relative thereto in correspondence. withchanges in the diameter of the work piece,. a pattern .movable with the base. piece and havinga. shape corre? sponding .to the desired shape of the work. piece, amember jointly positioned by said plunger and pattern, and means under the control of said member for relatively moving the tool and work piece.

17. In a metal forming machine including a tool and a support therefor movable relative to the machine so that the tool may perform a cutting operation, means by which the tool is caused to traverse a predetermined path to form a work piece corresponding to the form of a pattern comprising, a gaging block adapted to traverse the work piece as the tool traverses the work piece, an index member carried by said block and in engagement with the work piece so arranged that it is moved relative to the gaging block in accordance with changes in the shape of the work piece, a support for the pattern positioned by the gaging block as the latter is moved in correspondence with changes in the work piece, and means under the joint control of said pattern and index member for relatively moving the tool and work piece.

18. A tracer mechanism as defined in claim 9 wherein the differential mechanism includes a pivoted baiile and fluid jets of normally constant pressure discharging to atmosphere, the discharge pressure of said jets controlling the relative movements between the tool and the work piece, the relative position of said pivoted baflie for moving said tool relative to said carriage includes fluid jets of normally constant pressure discharging to atmosphere mounted adjacent the said. bell crank whereby movement of the said $3 crank varies the discharge rate of said fluid 20. The combination as defined in claim 11 wherein one arm of the said pivoted bell crank overlies a pair of fluid jets of normally constant pressure discharging to atmosphere and the movement of said bell crank arm varies the disto the relative positions ofsaid plunger and Y- (6 charge rate of said jets for controlling the movecontour of a work piece. the combination therea with of a follower movable with said carriage and engaging said pattern, an arm pivoted to said follower and rotatedthereon by the contour of the work piece, said pivoted arm having an ex tension forming a baflie, a pair of fluid jets of normally constant fluid pressure discharging to atmosphere mounted adjacent the said pivoted baiiie arm whereby movement thereof will vary the discharge pressure of the said jets, the relative movements of the carriage and the position of the tool relative to the work piece being controlled by the discharge pressures of said jets.

22. A duplicator for machine tools as defined in claim 16, wherein the member jointly positioned by said plunger and pattern comprises a pivoted arm overlying a pair of fluid Jets of normally constant pressure discharging to atmos-- phere whereby movement imparted to the pivoted arm by said plunger varies the discharge rate in claim 16, wherein the member Jointly posi of said let: for controlling the relative movement or th tool and work piece.

23. A duplicator. for machine tools as deiined tioned by said plunger and pattern comprises a fluid pressure control couple having fluid jets of normally constant pressure discharging to atmosphere, a substantially vertical arm pivoted to the base part of the said gaging device, the lower part or said arm contacting and receiving movement from said plunger, the upper part of said arm lying adjacent to and across the said fluid jets whereby movement imparted to the upper part of said arm varies the discharge pressure of said jets for controlling the relative movement of the tool and work piece.

24. A duplicator for machine tools and the like having a relatively movable tool and workpiece. a pattern, motor mean; to cause relative movement of said tool and workpiece, a. control couple including a feeler for the pattern and a i'eeler for the workpiece, the elements of said couple being interrelated to control said motor means to cause relative movement between said tool and workpiece.

CLARENCE JOHNSON. 

